Large Super Low Noise commercial fans which are used in commercial air cooled apparatuses such as cooling towers, air cooled heat exchangers, including large radiator air coolers and air cooled steam condensers, have a diameter greater than four feet and have blades with forward swept concavely curved leading edges. The forward swept concave leading edges reduce the noise generated by such fan blades. A forward swept leading edge is a leading edge that in inclined at an angle in the direction of fan rotation. A typical fan 1 having blades 2 having a curved forward swept leading edge 3 is shown in FIG. 1. As can be seen the leading edges have a concave forward sweep 4. The forward swept concave leading edge fan blades provide for the quietest fans. Fans with such blades are referred commonly referred to as “Super Low Noise fans” or alternatively as “Ultra Low Noise fans”. A description of such fan blades is provided in the article entitled “Blade Sweep of Low-Speed Axial Fans” by T. Wright and W. E. Simmons published in the January 1990 Journal of Turbomachinery, pages 151 to 158, and the paper entitled “Reduction of Noise Generation By Cooling Fans” by Ir. Henk F. Van der Spek, presented at the 1993 Cooling Tower Institute Annual meeting. These articles are fully incorporated herein by reference. These blades are typically fabricated from fiberglass with a polyester resin to allow easier molding into their complex shape. Moreover these blades are rigidly mounted to a fan hub. Consequently these Super Low Noise fans, which are currently the quietest available, are heavy and expensive to fabricate. Because of their weight, they are cumbersome to install, requiring cranes or heavy equipment, and unbalances can generate substantial loads on the supporting structure and bearings which can lead to structural failure and/or reduced fan bearing life.